import java.io.*
 
fun main() {
    val br = System.`in`.bufferedReader()
    val bw = System.`out`.bufferedWriter()
    val (n, m) = br.readLine().split(" ").map { it.toInt() }
 
    val nameMap = mutableMapOf<String, Int>()
    repeat(n) {
        val name = br.readLine()
        nameMap[name] = 1
    }
 
    val result = mutableListOf<String>()
    repeat(m) {
        val name = br.readLine()
        if (nameMap[name] != null) {
            result.add(name)
        }
    }
 
    bw.write("${result.size}")
    bw.newLine()
    for (name in result.sorted()) {
        bw.write(name)
        bw.newLine()
    }
    bw.flush()
    bw.close()
}

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3 4
ohhenrie
charlie
baesangwook
obama
baesangwook
ohhenrie
clinton